In the related art, there is a known technique related to a waveguide filter applied to a high frequency signal. As such a technique, there is a known technique of promoting miniaturization of a waveguide filter by bringing a circuit board close to the waveguide filter.
In addition, there is a known technique of adjusting a resonance frequency by installing an adjusting screw on a waveguide filter.
Japanese Laid-open Patent Publication No. 2003-289204, Japanese Laid-open Patent Publication No. 2005-260570, Japanese Laid-open Patent Publication No. 2013-106114, and Japanese Laid-open Patent Publication No. 2004-22587 are examples of related art.